The present invention relates to the updating of encryption keys within an Asynchronous Transfer Mode (ATM) system using for example ATM Virtual paths or Virtual circuits which allows very simple ways to update and manage encryption keys without the usual problem of synchronizing changes between transmitters and receivers of information.
If data is being encrypted, transmitted across a system and then decrypted at the other side as in FIG. 1, this is straightforward if the encryption keys are constant. However, for a system that has to operate for some time there will be a desire to change the key from time to time. In prior art systems this has been done by transmitting the new key across the system, pre-loading the second key at the destination and giving some changeover signal. Then the receiver has to be able to hold two keys and to change over between them very fast, in a carefully controlled manner, without losing data. Synchronizing the changeover between the two ends is the real problem.
Document entitled xe2x80x9cDesign of a Key Agile Cryptographic System for OC-12c Rate ATMxe2x80x9d, by Stevenson, et al., Proceedings of the Symposium of Network and Distributed System Security, San Diego, USA, February 1995, pages 17-30 describes an experimental key agile cryptographic system under design at MCNC. The system is compatible with ATM local- and wide-area networks. The system establishes and manages secure connections between hosts in a manner which is transparent to the end users and compatible with existing public network standards.
A Cryptographic Unit supports hardware encryption and decryption at the ATM protocol layer. The system is SONET compatible and operates full duplex at the 0C-12c rate (622 Mbps). Separate encryption keys are negotiated for each secure connection. Each Crytographic Unit can manage more than 65,000 active secure connections. The Cryptographic Unit can be connected either in a security gateway mode referred to as a xe2x80x98bump-in-the-fibrexe2x80x99 or as a direct ATM host interface. Authentication and access control are implemented through a certificate-based system.
According to the present invention there is provided in an Asynchronous Transfer Mode (ATM) telecommunications network having a plurality of virtual paths, a method of updating an encryption key used for data transmitted between a source and a receiver, the data being transmitted initially using a first encryption key, by a first of the plurality of virtual paths and a connection being established by a second of the plurality of virtual paths, by which connection a second encryption key is sent from the source to the receiver and subsequently the data being transmitted using the second encryption key by the second of the plurality of virtual paths.
There is further provided, in an Asynchronous Transfer Mode (ATM) telecommunications network having a plurality of virtual circuits, a method of updating an encryption key used for data transmitted between a source and a receiver, the data being transmitted initially using a first encryption key, by a first of the plurality of virtual circuits and a connection being established by a second of the plurality of virtual circuits, by which connection a second encryption key is sent from the source to the receiver and subsequently the data being transmitted using the second encryption key by the second of the plurality of virtual circuits.
FIG. 1 shows a prior art method of encryption; and
FIG. 2 illustrates the sequence of operations followed in the method of the present invention.